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Sem 1 - Body Logistics > 16 - Lymphatic System > Flashcards

16 - Lymphatic System Flashcards

1
Q

What is the lymph system made up of?

A
  • Lymph
  • Lymph vessels (lymphatics)
  • Organs
  • Lymphocytes
  • Follicular dendritic cells and macrophages
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2
Q

What is lymph?

A

Similar to plasma. Excess fluid collected from the interstitial space.

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3
Q

What are the primary and secondary organs of the lymphatic system, and what are the functions of primary and secondary?

A

Primary:

  • Thymus + Bone marrow
  • Generate lymphocytes from immature progenitor cells that arise from stem cells in the bone marrow

Secondary:

  • Spleen + Lymph Nodes
  • Site of lymphocyte activation and provide environment for antigens to interact with lymphocytes
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4
Q

What is tertiary lymphoid tissue?

A

Formed during autoimmune diseases, e.g rheumatoid arthiritis. Assume a role when challenged with antigens tha result in inflammation.

Ectopic lymphoid follicles

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5
Q

What is the function of the thymus and what happens to it over a life span?

A
  • Located in superior mediastinum
  • Thymic cell education (matures T-cells) and induction of central tolerance
  • Increases in size from birth due to post-natal antigen stimulation, atrophy by teenage years, by adult thymic stroma is mostly replaced by adipose tissue
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6
Q

What is the structure of the thymus?

A

Lobules joined by septa and encapsulated by a capsule.

Capsule and Septa made mainly by reticulun fibres in ECM

ONLY HAS EFFERENT LYMPH VESSELS

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7
Q

What is the structure of the spleen and where is it located?

A

Left side of abdomen, posterior to stomach, inferior to diaphragm.

ONLY HAS EFFERENT LYMPH VESSELS

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8
Q

What is the function of the spleen?

A

FILTER BLOOD LIKE LYMPH NODE FILTERS LYMPH

Haemopoietic:

  1. Remove of old, abnormal, damaged blood cells
  2. Store erythrocytes
  3. Retrieve Fe from Hb
  4. Produce blood cells up to 5 months foetus

Immune:

  1. Removing big antigens from blood using macrophages
  2. Antigen presenttion
  3. Activation and proliferation of lymphocytes
  4. Produce immune cells
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9
Q

What is a germinal centre?

A

Sites within secondary lymphatic organs where B-cells proliferate and undergo monoclonal selection

Contain memory cells and IgA produced here

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10
Q

What is splenomegaly?

A

Where the spleen enlarges in response to localised/systemic infection due to proliferation B-cells.

Can lead to rupturing and exsanguiation

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11
Q

What would you do with a ruptured spleen and why would you try to avoid it?

A

Splenectomy

  • Needed in case it ruptures and causes internal bleeding
  • Removal leads to increased risk of infection by encapsulated bacteria and malaria
  • Liver can take over haemolysis
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12
Q

What is the structure of a lymph node?

A
  • Several afferent vessels, lymph follicles in cortex, medulla, hilum, single efferent vessel.
  • Arteries and veins enter node via hilum
  • Reticulin CT
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13
Q

How many lymph nodes are there and where are they mainly located?

A
  • 600-700
  • Cervical, Inguinal, Axillae
  • Clusters anywhere that lymph is collected from regions likely to sustain pathogen contamination
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14
Q

What are sentinel lymph nodes?

A

Lymph nodes closest to major organs, that interact with foreign antigens or tumour cells.

First lymph node to interact with metastasising cancer.

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15
Q

What is the function of a lymph node?

A

Acts as a filter as the lymph goes back to the vascular system. Traps antigens and mediates immune response using macrophages, T-cells and B-cells

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16
Q

What is an enlarged lymph node called and why is it enlarged?

A
  • Lymphadenopathy
  • Proliferation of T and B-cells in germinal centres because of infection
  • Can also be due to metastatic tumours in nodes
  • Can be due to lymphoma
  • Painful
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17
Q

What is local and generalised lymphadenopathy?

A

Local: Few nodes locally are enlarged due to infection

Generalised: Nodes in different areas enlarged. Can be due to cancer or infection

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18
Q

What is MALT?

A

Mucosae-associated LT

  • Beneath epithelia in submucosa are lymphoid follicles
  • Nodule contains lymphocytes, plasma cells, macrophages
  • Tonsils, Peyers Patches (ileum), Appendix
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19
Q

What do follicular dendritic cells do? APC

A
  1. Take pathogen into lymph node to macrophage zone
  2. Activate T-cells which can then activate B-cells
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20
Q

What are the main differences between T and B cells?

A
  • B cells recognise antigens, T cells do not
  • T cells attack invades in cell, B-cells attack outside evaders
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21
Q

What are tonsils?

A
  • Collection of lymphoid tissue near throat and facing into oral cavity.
  • Have M-cells and crypts to increase SA
  • Function is to prevent ingress of pathogens through ears, nose and throat
22
Q

What is Waldeyer’s Tonsillar ring?

A
  • 2 Palatine (posterior end of oral cavity)
  • 1 Lingual (back of tongue)
  • 1 Adenoid (posterior wall of nasopharynx)
  • 2 Tubal (opening of auditory tubes into pharynx)
23
Q

Why are tonsils poorly encapsulated, apart from tubal?

A

Allow ingress of pathogens and egress of immune cells.

Poor capsulated areas are where M cells are. Capture antigens and present them to underlying immune cells

24
Q

Where is the vermiform appendix and what is it’s structure?

A

Where?

Attached to area where SI and LI attach.

What?

Tube that has longitudinal and circular smooth muscle laying over submucosa. Nodules below crypts and M-cells on surface

Why?

Prevent ingress of pathogens,

25
Q

What are Payer’s patches?

A
  • In SI
  • Epithelia above is M cells that are simple cuboidal, not columnar like rest of SI, so no microvilli, glycocalyx etc
  • Large number of B-cell follicles. Few T-cells between follicles.
  • Prevent ingress of pathogens
26
Q

How do M cells work in context of Peyer’s patches?

A
  1. Trap pathogen by phagocytosis
  2. Present pathogen to T/B-cells in basement membrane
  3. Activated lymphocytes can enter lymphatics below and generate immune response
27
Q

What are the four functions of the lymphatic system?

A
  1. Removal of interstitial fluid and replacement
  2. Absorb and transports fats as chyle from DT
  3. Storage and destruction of RBC
  4. Defence against pathogens
28
Q

How does lymph travel?

A
  • Located close to veins and arteries pulse causes tissue near lymph vessel to contract and so does the vessel
  • Deep lymph vessels rely on muscle contraction
  • Large ducts and trunks have smooth muscle
  • Pressure changes during breathing
29
Q

What area of the body has no lymphatic drainage?

A

CNS, to prevent oedema

30
Q

Where does lymph flow to and from?

A

Lymphatics lie adjacent to cardiac vessels

31
Q

Describe structure of a lymph vessel?

A
  • Blind ended
  • Intraluminal valves for uni flow (muscle in collecting vessels)
  • Overlapping endothelial cells (flaps)
32
Q

Compare a lymph vessel and vein

A
  • Smaller
  • Not as much smooth muscle
  • Less/no cells
  • Both have fibrocartilagenous valves
  • Flaps between endothelial cells
33
Q

What are the two main collecting vessels and where do things drain into them from?

A

- Thoracic Duct (Left) : Left sub-clavian. Rest of body.

- Right Lymphatic: Right sub-clavian. Upper right quadrant above cisterna chyli

USEFUL TO KNOW FOR DIAGNOSIS!!

34
Q

What is the cisterna chyli?

A

Recieves lymph drainage from digestive organs, chyle!

Links to thoracic duct

35
Q

What is chyle?

A

Milky fluid consisting of lymph and emulsified fats from lacteals of small intestine

36
Q

How is fat absorbed in the small intestine?

A

Fats asorbed into lymph and move through it in chylomicrons.

Chylomicrons drain to cisterna chyli, then thoracic duct and then to left subclavian vein so miss livers first metabolism

37
Q

What is the difference between a lymphoma and a leukemia?

A

Lymphoma - Cancer of lymphatic tissue

Leukaemia - Cancer in lymphatic tissue but originates from bone marrow

38
Q

What is the difference between Hodgkin and Non-Hodgkin Lymphoma?

A

Hodgkin:

  • Presence of Reed-Stenburg cell
  • Associated with past infection and lymphadenopathy

Non-Hodgkin:

  • Increased proliferation of B and T cells
  • Old age
  • Poor prognosis
39
Q

How can cancer end up in the lymph system?

A
  • Angiogenesis

OR

  • Invade into lymph vessels and release exosomes into node to make right environment
  • Melanoma cell goes down vessel into node, settles and proliferates

(breast, endometrial, malignant melanoma)

40
Q

How are sentinel (first nodes to swell) detected?

A
  • Old: frozen section in surgery and masectomy
  • New: Inject blue tagged glucose close to node before surgery. Blue will be taken up by cancer cells as fast proliferating. Remove only nodes with die
41
Q

What is lymphoedema, and what is a primary and secondary cause?

A

Accumulation of lymph, due to damaged or malformed lymphatic system.

Primary = Genetic predisposition

Secondary = caused by another disease or condition

42
Q

What are some primary lymphoedema?

A

- Congenital (Milroy) : onset in 2 years, mutation in FLT4 gene (VEGF-r) so missing endothelial cells for vessels

- Praecox (Meige’s): 2-35 years, unknown, familial

- Tarda: After 35, unknown

43
Q

Whar are some secondary lymphoedema causes?

A
  • Lymphatic Filariasis
  • Cellulitis
  • Removal of nodes in cancer treatment
  • Accidental damage to lymphatics during surgery
  • Radiotherapy
  • Flying after cancer treatment
44
Q

How can lymphoedema be treated?

A

NO CURE JUST IMPROVE SYMPTOMS

  • Manual drainage by massage (not permanent)
  • Stockings
  • Exercise to get muscles moving
45
Q

Label all the parts of the lymphatic system.

A
46
Q

What is the innate immune system?

A
  • Non-specific first line of defence
  • Physical barriers, Phagocytes, NK cells
  • Fever, Inflammation
47
Q

What is the inflammatory response in basic terms?

A

It is part of the innate response

  • Mast cells in CT release histamines which cause vasodilation and increased permeability of capillaries
  • Vasodilaiton causes red, permeability causes fluid build up
  • Fluid build up allows phagocytes to enter and clotting
48
Q

What is the humoral immune response?

A
  • One part of adaptive immune system
  • Involves B-cells recognising antigens and releasing antibodies
  • Produces memory cells and plasma cells
  • Antibodies released either neutralise or agglutinate
  • Allows immunity
49
Q

What is the cell mediated response?

A
  • Macrophages present antigens to T-lymphocytes
  • T-cells divide and form cytotoxic or helper cells
  • Cytotoxic kill (releasing enzymes and perforating so apoptosis) and helper activate other cells by releasing cytokines
  • Some memory cells formed
50
Q

What are the differences between humoral and cell-mediated immune response?

A
51
Q

Where is the vermiform appendix and what is it’s function?

A

Contains lymphatic nodules with germinal centres so must be part of the lymphatics

Sem 1 - Body Logistics (20 decks)

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